Tetrahydropyrimidyl-substituted compounds

ABSTRACT

A new class of compositions, tetrahydropyrimidyl-substituted compounds, useful as ashless bases and rust inhibitors, is prepared by reacting a C3-to C50 amine containing a 1,3-diaminopropane group with ethylenediamine tetraacetic acid or nitrilotriacetic acid at a temperature of 150 DEG  to 250 DEG  C. for 10 to 100 hours.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of application Ser. No. 845,700 filedOct. 26, 1977 which, in turn, is a Continuation-in-Part of application,Ser. No. 610,761 filed Sept. 8, 1975, now abandoned, which, in turn, isa Continuation-in-Part of application Ser. No. 431,831, filed Jan. 7,1974, now abandoned.

BACKGROUND OF THE INVENTION

Varnish, sludge, rust and corrosion seriously reduce the efficiency ofan internal combustion engine by clogging restricted openings andreducing the clearance of moving parts. A high-quality motor lubricatingoil must incorporate detergents capable of controlling varnish formationand corrosion. This function has heretofore been mainly performed bycertain metallo-organic salts and bases in the lubricating composition.However, the present trend to unleaded fuels and ashless lubricatingcompositions brought about by certain important environmental concernsnecessitates the search for non-metallic (ashless) substitutes for themetallo-organic detergents. These non-metallics must fulfill a host ofrequirements, primary among which are basicity and thermal stability.

DESCRIPTION OF THE PRIOR ART

U.S. Pat. No. 2,844,446 discloses bis-tetrahydropyrimidines wherein therings are joined by a hydrocarbon radical of at least 2 carbon atoms.The bis-tetrahydropyrimidines are prepared by condensing 2 mols of analkaline polyamine having at least 1 primary amino group separated fromanother primary or secondary amino group by 3 carbon atoms with 1 mol ofa dicarboxylic acid at a temperature above 175° C. 1,3-Propylenediamineis disclosed as a suitable amine. Suitable polycarboxylic acids includeoxalic, glutaric, adipic, higher polybasic carboxylic acids, and thelike. The bis-tetrahydropyrimidines of this invention are useful inhydrocarbon distillates for retarding or preventing discoloration,oxidation, rust or corrosion, and in addition to impart detergentproperties. In lubricating oils, the additive may function as apour-point depressant, viscosity-index improver, etc.

U.S. Pat. No. 3,325,496 teaches the use of triaminopyrimidines ashigh-temperature lubricant fluids.

U.S. Pat. No. 2,830,019 teaches the production of amine salts from thereaction of an aliphatic or heterocyclic amine with anitrogen-containing polycarboxylic acis such as ethylenediaminetetraacetic acid.

SUMMARY OF THE INVENTION

It has been discovered that tetrahydropyrimidyl-substituted compoundsprepared from a C₃ to C₅₀ amine containing a 1,3-diaminopropane groupand ethylenediamine tetraacetic acid (EDTA) or nitrilotriacetic acid(NTA) are exceptionally superior ashless base additives for lubricatingoil having good thermal stability as well as basicity.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The tetrahydropyrimidyl-substituted compounds of this invention areprepared by reacting ethylenediamine tetraacetic acid ornitrilotriacetic acid with a compound of Formula I: ##STR1## whereineach of R, R¹, R² and R³ is independently hydrogen or hydrocarbyl. Thereaction is carried out at a temperature of 150° to 250° C. for 10 to100 hours. The reaction product may be used directly in the lubricatingcompositions of this invention, or it may be purified by methods wellknown in the art to substantially isolate the primarypolytetrahydropyrimidine product. In generally, the use of the reactionproduct per se is preferred.

The compositions of this invention are found to function as superiorashless additives for lubricating oil compositions in that they retainsubstantial alkalinity values under conditions of sustained hightemperatures and they are highly rust-inhibitory.

The products of this invention are composed of compounds of thefollowing formulas, wherein Formula II representes the primary productfrom the reaction of nitrilotriacetic acid with the 1,3-diaminopropanecompound of Formula I. Formula III represents the primary product fromthe reaction of ethylenediamine tetraacetic acid with the1,3-diaminopropane compound of Formula I. ##STR2##

In the above formulas, each of R, R¹, R² and R³ is hydrogen orhydrocarbyl. As used herein, hydrocarbyl represents a radical composedprimarly of carbon and hydrogen and containing from 1 to about 50 carbonatoms per hydrocarbyl group. The hydrocarbyl group is preferablysaturated; however it may contain 1 or 2 sites of olefinic unsaturation.Preferably the hydrocarbyl group is an alkyl group of from 1 to 30carbon atoms, and more preferably of from 1 to 20 carbon atoms. Suitablesubstituents include methyl, hexadecyl, tetrapropenyl, hexabutenyl,ethylbenzyl, and the like. Without altering the basic performancecharacteristics of the compositions of this invention, each of R, R¹, R²and R³ can be a hydrocarbyl group which is substituted by 1 to 2alkylamino, alkyloxy or hydroxyalkyl groups, e.g., ethylamino,hydroxyethyl, ethyloxy, and the like. Preferred compositions are thoseprepared from an N-substituted 1,3-diaminopropane, i.e., those compoundswherein R is hydrocarbyl and R¹, R² and R³ are each hydrogen. Thepreparation of the compositions of this invention is carried out bymixing EDTA or NTA and the amine in a suitable solvent, such as xylene,while maintaining the temperature at about 150° to 250° C. for about 10to about 100 hours, preferably from about 20 to about 40 hours. Thereaction temperature is, of course, generally limited by the refluxtemperature of this solvent or the decomposition temperature of thereactants or product. It is preferred to react all of the carboxylicacid groups; therefore it is preferred to operate with an excess ofamine over the stoichiometric requirement. Broadly, from 0.9 to 3 molsof amine per carboxylic acid group is utilized, and preferably 1.5 to 2mols. The product is complex, containing intermediate amides and othercompounds in addition to mixed tetrahydropyrimidino compounds.

EXAMPLES

The preparation of illustrative compositions in the scope of thisinvention is illustrated by the following examples. It is not intendedthat these examples represent limitations on the embodiments of thisinvention.

EXAMPLE 1

Into 600 ml of xylene were placed 57 g (about 0.3 mol) of nitriloaceticacid and 360 g (about 0.9 mol) of N-oleyl-1,3-diaminopropane. Themixtures was held at about 150°-200° C. for about 27 hours and a totalof 30 ml of water was evolved (calculated, 35 ml). The 431 g of producthad 7.4 weight percent of nitrogen and an alkalinity value of 160 mgKOH/g. The infrared specturm showed the strong C=N band at 1640 cm⁻¹,and nuclear magnetic resonance (NMR) confirmed the presence of themethylene-ring hydrogens of the tetrahydropyrimidinyl group.

EXAMPLE 2

N-oleyl-1,3-diaminopropane (2400 g, about 6 mols) and nitrilotriaceticacid (282 g, about 2 mols) were mixed under nitrogen with stirring to200° C. over a 2-hour period. The mixture was maintained at thistemperature for about 18 hours, stripped under vacuum and nitrogen to150° C., and 2661 g of product was recovered having an alkalinity valueof 176 mg KOH/g. The product istris-(3-oleyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)amine with someintermediate amides.

EXAMPLE 3

Into 300 ml of xylene were mixed 146 g of ethylenediamine tetraaceticacid (about 0.5 mol) and 800 g of N-oleyl-1,3-diaminopropane. Themixture was heated at 150°-200° C. for about 48 hours, and 69 ml ofwater was evolved (72 ml calculated). The 904 g of product had analkalinity value of 180 mg KOH/g and showed the infrared absorption at1630 cm⁻¹ typical of C=N. The product isN,N,N',N'-tetrakis-(3-oleyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)ethylenediamine, mixed with some amido intermediates.

EXAMPLE 4

In 100 ml of xylene were mixed 56 g (about 0.29 mol) of nitrilotriaceticacid and 212 g (about 0.88 mol) of N-tallow-alkyl-1,3-diaminopropane.The mixture was heated to about 200° C. for about 27 hours. 31 ml ofwater was evolved (31 ml calculated). The 330 g of product contained aninfrared absorption at 1640cm⁻¹. The product istris-(3-tallowyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)amine with someamido intermediates.

EXAMPLE 5

The 20 ml of xylene were added 191 g (about 1 mol) of nitrilotriaceticacid and 834 g (about 3 mols) of N-coco alkyl-1,3-diaminopropane. Themixture was heated for about 29 hours at about 200° C. 101 ml of waterevolved (108 ml calculated). The 911 g of product had an alkalinityvalue of 187 and contained 3.5 weight percent of nitrogen. The productcontained a sharp infrared absorption at 1630 cm⁻¹. It istris-(3-coco-2,4,5,6-tetrahydro-2-pyrimidylmethyl)amine.

Evaluation

The polytetrahydropyrimidinyl products prepared by the process of thisinvention display satisfactory anti-varnish detergency as additives inlubricating oils for the internal combustion engine as illustrated inthe Ford V* varnish test results of Table I. In this test, a Ford V8engine of 302 cubic inches displacement is operated in cycles of500/2500/2500 rpm for periods of 45/120/75 minutes on a Chevron gasolinecontaining FCC heavy fraction (i.e., product of fluidized-bed catalystcracking.

                  TABLE I                                                         ______________________________________                                        Ashless Base in Ford V8 Varnish Test                                                         Varnish Rating at (hours)                                                     20    40      60      80                                       ______________________________________                                        No base.sup.1    8.9     8.0     <7.7  --                                     Metallic base.sup.2                                                                            9.7.sup.4                                                                             9.4     9.1.sup.4                                                                            8.8.sup.4                             Polytetrahydropyrimidine.sup.3                                                                 9.6     8.9     8.7   8.3                                    ______________________________________                                         .sup.1 All oils contained 6 weight percent polyisobutenyl succinimide of      tetraethylene pentamine and 15 mM/kg of zinc dialkyldithiophosphate in a      neutral petroleum oil.                                                        .sup.2 30 mM/kg of carbonated, sulfurized, calcium polypropylene phenate      (9.25% calcium) and 30 mM/kg of overbased calcium sulfonate (11.4%            calcium).                                                                     .sup.3 Tris(3-oleyl-3,4,5,6-tetrahydro-2-pyrimidylmethyl)amine at 2 weigh     percent (63 meg/kg).                                                          .sup.4 Mean value of two runs.                                           

In the Ford V8 varnish test, the engine is disassembled at 20-hourintervals and the piston varnish is measured on a scale of 0-10, with 10being completely clean. The polytetrahydropyrimidine ashless base isfound to give anti-varnish protection which is comparably satisfactoryto the metallic base-containing, e.g., overbased, lubricating oilcompositions in present use.

The polytetrahydropyrimidines display excellent rust-inhibitory abilityin the ASTM D1748 Humidity Cabinet Rust Test. In Table II, variouslow-ash and ashless lubricating oil compositions have been tested in theHumidity Cabinet Rust Test with and without the addition of 1% by weightof the product of Example 1.

                  TABLE II                                                        ______________________________________                                        Rust Inhibition of Polytetrahydropyrimidine (1%)                                           Humidity Cabinet Rust Life                                                    (hours)                                                          Composition    Without    With                                                ______________________________________                                        Low-Ash.sup.1  <24        (50)                                                Low-Ash.sup.2  <24        (90)                                                Ashless.sup.3  24         (800)                                               Ashless.sup.4  40         (700)                                               Ashless.sup.5  130        (>2000)                                             ______________________________________                                         .sup.1 6 weight percent of polyisobutenyl succinimide of                      tetraethylpentamine and 18 mM/kg of zinc dialkyl dithiophosphate.             .sup.2 The composition of Footnote 1 + 0.2 weight percent of                  tetrapropenylsuccinic acid.                                                   .sup.3 5 weight percent of polyisobutenylsuccinimide of                       triethylenetetraamine, 1 weight percent of diisobornyldiphenylamine and 1     of bisalkylphenol sulfide.                                                    .sup.4 The composition of Footnote 3 + 0.2 weight percent of                  tetrapropenylsuccinic acid.                                                   .sup.5 6 weight percent polyisobutenylsuccinimide of                          tetraethylenepentamine, 1 weight percent sulfurized wax, 3 weight percent     sulfurized alkylphenol and 1.5 weight percent hindered bisphenol (Ethyl       702).                                                                    

The humidity cabinet rust lifetime in hours for the same compositioncontaining 1% of the polytetrahydropyrimidines is given in parenthesesin Table II. Even the low-ash and ashless compositions containingtetrapropenylsuccinic acid are found to be improved in rust inhibitionby the addition of only 1% of the polytetrahydropyrimidine.

                  TABLE III                                                       ______________________________________                                        Rust Inhibition of Polytetrahydropyrimidine                                                    Humidity Cabinet Rust                                        Additive at 1%   Life (Hours)                                                 ______________________________________                                        None.sup.1       <24                                                          Example 2        300                                                          Example 4        270                                                          Example 5        200                                                          Example 3        250                                                          ______________________________________                                         .sup.1 A neutral petroleum oil of about 480 SUS at 100° F.        

The rust-inhibitory power of the polytetrahydropyrimidines of Examples2-5 is demonstrated in the Table III.

The alkalinity value (AV) of a base is an important indicator of theability of the additives to inhibit corrosion, varnish formation andrust. The alkalinity value is obtained by titrating the material withperchloric acid in glacial acetic acid. The results are converted to mgKOH/g necessary to neutralize the titrated acid. Just as important as ahigh alkalinity value in a lubricating composition is the ability of thebase to maintain its AV over a period of time under the extreme thermalconditions encountered in actual use.

                  TABLE IV                                                        ______________________________________                                        Thermal Stability                                                                                 Initial                                                                       Alkalinity                                                Additive.sup.1      Value (AV) Retention                                      ______________________________________                                        Polyisobutenyl succinimide                                                     of tetraethylene pentamine                                                                       9.1        67%                                            Polyisobutenyl ethylenediamine                                                                    4.4        25%                                            Example 2           16         72%                                            Example 4           17         79%                                            ______________________________________                                         .sup.1 All additives are at 10 weight percent in a neutral mineral oil.  

The results of Table IV illustrate the outstanding thermal stability ofthe polytetrahydropyrimidines in comparison with other ashless bases.Lubricating oil compositions containing a neutral mineral oil and 10% ofthe additive in Table IV were maintained at 300° F. for 24 hours. Theinitial and final AV was measured and the result expressed as a percentretention of AV under these conditions. The polytetrahydropyrimidinesdisplay an outstanding retention of alkalinity value.

Prior Art Example

The example taught at Col. 5, lines 4-11, of U.S. Pat. No. 2,830,019 wassubstantially repeated as follows:

Into a 1-liter flask were placed 251.3 g (0.86 mol) of ethylenediaminetetraacetic acid and 166.1 g (0.46 mols) of Duomeen S. The mixture wasstirred and heated to 155° C. for 20 minutes. The reaction product wassolid and was insoluble in oil. IR, NMR and UV analyses indicated aproduct consisting primarily of amides with some salts. Therust-inhibitory ability of the product was tested using ASTM D1748Humidity Cabinet Rust Test as in Table II above. The humidity cabinetrust life was less than 24 hours.

Additive Medium

The products of this invention may be used singly or in combinations oftwo or more in an oil of lubricating viscosity. The lubricating oil canbe any relatively inert and stable fluid of lubricating viscosity. Suchlubricating fluids are generally of viscosities of 35-50,000 SayboltUniversal Seconds (SUS) at 100° F. (37° C.). The fluid medium or oil maybe derived from either natural or synthetic sources. Included among thenatural hydrocarbonaceous oils are paraffin-base, naphthenic-base ormixed-base oils. Synthetic oils include polymers of various olefins,generally of from 2 to 6 carbon atoms, alkylated aromatic hydrocarbons,etc. Non-hydrocarbon oils include carboxylic acid esters, polyalkyleneoxides, phosphates, aromatic ethers, silicones, etc. The preferredlubricating media are the hydrocarbonaceous media, both natural andsynthetic. Preferred are those hydrocarbonaceous oils having viscositiesof about 100-4000 SUS, and particularly those having viscosities of from200 to about 2000 SUS at 100° F. The lubricating fluids may be usedindividually or in combinations when intermiscible or made so by the useof mutual solvents.

The lubricating oil will be present at 75 or greater percent by weightof the final composition. In concentrates, however, the oil may bepresent at 1-84%, preferably 1-50%, by weight. These concentrates arediluted with additional oil prior to being placed in service to obtainthe requisite concentration.

Other additives may also be present in the compositions of thisinvention. Materials may be added for enhancing the EP properties of thecomposition, or providing other desirable properties to the lubricatingmedium. These include such additives as rust and corrosion inhibitors,anti-oxidants, oiliness agents, detergents, rust inhibitors, theviscosity-index improvers, pour-point depressants, etc. Usually thesewill be in the range of from about 0-5%, more generally in the range offrom about 0-2%, of the total composition. Typical additional additivesfound in compositions of the present invention include phenolic andarylamine antioxidants and ashless dispersents such as thealkenylsuccinimides. The polytetrahydropyrimidines of the presentinvention may find use in lubricating compositions containing ash suchas the metallo-organic detergents which are known in the art, e.g., thealkaline earth phenates or sulfonates.

The additives of the present invention will generally be present inlubricating oils in functional amounts consistent with their use asashless bases and rust inhibitors. Such functional amounts willgenerally range from about 0.05 to 15 weight percent of the totalcomposition, more usually in the amount of about 0.1 to about 10 weightpercent of the total composition.

What is claimed is:
 1. A compound of the formula ##STR3## wherein R, R¹,R² and R³ are independently hydrogen or radicals composed primarily ofcarbon and hydrogen and containing from 1 to about 50 carbon atoms. 2.The compound of claim 1 wherein R is a radical composed primarily ofcarbon and hydrogen and containing from 1 to about 50 carbon atoms andR¹, R² and R³ are hydrogen.
 3. The compound of claim 2 wherein R is analkyl group of 1 to 20 carbon atoms.
 4. The compound of claim 2 whereinR is selected from oleyl, tallow and coco groups.